Guwahati/New Delhi, April 30: A helicopter carrying Arunachal Pradesh chief minister Dorjee Khandu has disappeared, triggering a roller-coaster of statements that first said it had landed safely in Bhutan and hours later classified its status as “missing”.

Such was the impact of the initial all-clear that the search-and-rescue drive was suspended. By the time the revised version emerged, there wasn’t enough light to resume the operation, which is expected to be re-launched in daylight tomorrow, highly placed sources said.

Besides Khandu, 56, who heads a Congress government in the sensitive border state, there were four people on the aircraft of Pawan Hans, one of whose helicopters had crashed 11 days ago in the same state, killing 17 people. Those on board with the chief minister this morning were pilots J.S. Babbar and K.S. Malick, Khandu’s security officer Yeshi Choddak, and an MLA’s relative, Yeshi Lamu.

Khandu was flying from Tawang in Arunachal to state capital Itanagar. The chopper lost contact with air traffic control (ATC) at 10.15am, 20 minutes after take-off and 40 minutes before the scheduled landing.

A source at the Regional Meteorological Centre (RMC) in Guwahati said the pilots had not taken the mandatory weather briefing, perhaps because the skies had looked fine, although the Northeast is notorious for sudden weather changes.

Sources said the ATCs in Guwahati — as well as a Thimphu-based Indian Air Force Squadron Leader, Sachin Mehta — had reported they had no news of any chopper landing in Bhutan.

“The chopper is still missing and search operations are on,” Union home secretary G.K. Pillai said this evening.

“Abhi tak kuch khabar nahi (there is no news yet),” Khandu’s son, Pema Khandu, said around 10.20pm.

Confusion, however, reigned earlier in the day as Arunachal Pradesh chief secretary Tabom Bam announced in the afternoon that the chopper which had lost contact with ATC in the morning had landed safely at Daporijo in the Subansiri Valley of Arunachal Pradesh around 2.30pm.

Bam told The Telegraph that he has not been able to contact Khandu personally but the Sashastra Seema Bal (SSB) had confirmed that Khandu and those with him were safe. “The IGP (SSB) has confirmed he is safe. I have a hunch that he will be picked up by an air force chopper and flown to Itanagar by tomorrow,” Bam said in the afternoon. Around 7.20pm, he said he had no time to speak when asked about an update. The first information that Khandu was safe had come from Raj Bhavan.

Added to that was a statement from Pawan Hans spokesperson Sanjay Kumar who told The Telegraph in the afternoon that the chopper had made a “precautionary landing” and that “everybody was safe”. “The registration number of the chopper is VT-PST and the make is AS350B3. There was no problem with the chopper and our pilots landed safely. We don’t know the exact name of the place where it landed but everyone is safe,” Kumar said.

Speaking to The Telegraph in the evening, SSB IGP Sanjeev Singhal said, “In the initial information we had said the helicopter had landed somewhere along the Arunachal-Bhutan border and that everyone was safe. Subsequently, when we tried to pinpoint the location and the timing, there was no confirmation. The situation remains the same.”

Hage Khoda, commissioner, civil aviation, Arunachal Pradesh, said the area where the chopper had landed along the Arunachal-Bhutan border was about 15 nautical miles from Tawang. Sources in his office said the chief minister was being flown to Guwahati late in the afternoon, something which was denied by the Arunachal Pradesh deputy resident commissioner’s office in Guwahati. Three choppers, including two from the IAF, had earlier been pressed to locate the missing chopper, the sources said.

Sources in the Airport Authority of India in Guwahati, for its part, said the place where the chopper landed in East Bhutan was around 180km from Guwahati.

Khandu’s chopper went missing at Sela Pass, a fact which is contrary to rumours that he landed in Bhutan. Officials said how Khandu was even told that he should fly to Guwahati and then to Itanagar instead of taking the risky Sela Pass flight plan. But the chief said he would “save time” an official said.

Khandu had gone to Tawang to receive Lok Sabha Speaker Meira Kumar.

The pilots on the chopper, Eurocopter AS 350 B3, that went missing with Dorjee Khandu on board today had not taken the necessary “weather briefing”, a source at the Regional Meteorological Centre in Guwahati said.

“Pilots make a requisition for a weather report and submit the route which they plan on taking,” the source said. A flight plan is made and the pilots are given a briefing about the weather condition. Protocol demands that before flying, a Met officer, a communications officer and an officer of the aircraft or the aircraft company signs the flight plan, the source said.

“However, no such request was made today,” the source at the Regional Meteorological Centre at Borjhar in Guwahati said.

The weather information is required during take-off, and it informs the pilots of any significant weather conditions such thunderstorms en route, along with the destination helipad runway condition. “Pilots sometimes take off on their own without taking the brief in case of fair weather and this is what may have happened today,” the source said. The weather office at Itanagar said the weather was “fine and fair” today.

Pilots flying in various destinations in Arunachal Pradesh have to take the necessary brief from the Regional Meteorological Centre in Guwahati as the weather office in Arunachal Pradesh at Itanagar does not provide aviation services for aircraft.

Helicopter pilots said the skies over the Northeast, where flying conditions can change unpredictably and fast, are among the most challenging zones to fly over in India. Low and narrow valleys, high humidity, and turbulence makes flying tricky, they said.

“No amount of experience is ever enough for the Northeast,” said Pradeep Srivastava, a former army aviation pilot who had spent several years flying helicopters in the Northeast. The low valleys with heavy jungle vegetation and high humidity provide conditions that can give rise to clouds within minutes. An inflow of cold air currents can quickly turn the moisture into clouds that begin to rise upward from ground level.

“One valley may be clear, the next one might be cloudy. We often encounter such quick clouding in the mornings. You might also enter a clear valley and find clouds forming right ahead of you — abrupt clouding can happen within five minutes,” Srivastava said.

Pilots flying across the northeastern valleys also need to watch out for turbulence. Air currents may cause downdrafts or updrafts when one side of the mountain is heated by sunlight and the other remains in shadow. For helicopters, a typical flying altitude in the northeast might be 3,000 feet.

When caught in a downdraft, said Srivastava, a helicopter pilot would have just about a minute to take precautionary measures and move out of the downdraft.

A former Indian Air Force (IAF) helicopter pilot, who has several years of flying experience in the Northeast, told The Telegraph that flying in the mountains, particularly in bad weather, becomes a tricky affair. “During this time of the year during the pre-monsoon season, the weather becomes very unpredictable in the Arunachal hills because of sudden thunder squalls,” he said.

“The unpredictable weather calls for a high level of flying skills. You can take chances with the hills, you can take chances with the weather, but it may become suicidal to take chances with the weather and the hills at the same time. If it rains heavily then sometimes visibility reduces to even less than 100 meters,” the pilot, who now flies commercial choppers, said.

The Eurocopter AS 350 B3 is a new generation chopper and “there is absolutely no problem with the machine,” the pilot said.

Through the later part of the day today, the Union ministry of home affairs was in touch with Bhutan government officials. The Bhutan home minister is understood to have issued orders to all district governors to look for the missing chopper.

“ATCs in Guwahati and Calcutta had informed the Arunachal Pradesh principal resident commissioner’s office in Delhi that they had no news about any chopper landing in Bhutan,” a source in principal resident’s office in New Delhi said.

Thimphu-based IAF squadron leader Sachin Mehta, too, had informed the deputy resident commissioner’s office of the same, the sources said.

Senior civil and police officials met this evening in Itanagar to discuss the situation. Sources said a crisis management cell was formed at the meeting to monitor the situation. Senior ministers also had an emergency meeting at Khandu’s residential office late this evening. Arunachal Pradesh home minister Tako Dabi, PCC president Nabam Tuki and MP Takam Sanjay participated in the meeting.

After the meeting government spokesman and power minister Jarbam Gamlin said the state government had been in constant touch with the Centre as well as the government of Bhutan. Army, SSB, ITBP personnel would launch a massive search operation at the break of the dawn tomorrow while the IAF choppers would conduct recces, he said.

The meeting set up a crisis management cell with principal secretary to the chief minister, Yeshi Tsering, civil aviation commissioner Hage Khoda, home secretary A.K. Srivastav, IGP SBK Singh, DIGP (West) Robin Hibu, DIG (intelligence) Anil Shukla, city deputy commissioner Pawan Kumar Sain and SP Apang Tamut. The committee will be monitoring the situation under the overall guidance and supervision of chief secretary Tabam Bam.